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riscv: vdso.lds.S: remove hardcoded 0x800 .text start addr

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I believe the hardcoded 0x800 and related comments come from the long
history VDSO_TEXT_OFFSET in x86 vdso code, but commit 5b93049337
("x86 vDSO: generate vdso-syms.lds") and commit f6b46ebf90 ("x86
vDSO: new layout") removes the comment and hard coding for x86.

Similar as x86 and other arch, riscv doesn't need the rigid layout
using VDSO_TEXT_OFFSET since it "no longer matters to the kernel".
so we could remove the hard coding now, and removing it brings a
small vdso.so and aligns with other architectures.

Also, having enough separation between data and text is important for
I-cache, so similar as x86, move .note, .eh_frame_hdr, and .eh_frame
between .rodata and .text.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Tested-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Link: https://lore.kernel.org/r/20230912072015.2424-4-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Jisheng Zhang 2023-09-12 15:20:15 +08:00 committed by Palmer Dabbelt
parent 49cfbdc21f
commit 8f8c1ff879
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1 changed files with 8 additions and 9 deletions
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17
arch/riscv/kernel/vdso/vdso.lds.S
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@ -23,12 +23,8 @@ SECTIONS
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
.note : { *(.note.*) } :text :note
.dynamic : { *(.dynamic) } :text :dynamic
.eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
.eh_frame : { KEEP (*(.eh_frame)) } :text
.rodata : {
*(.rodata .rodata.* .gnu.linkonce.r.*)
*(.got.plt) *(.got)
@ -37,13 +33,16 @@ SECTIONS
*(.bss .bss.* .gnu.linkonce.b.*)
}
.note : { *(.note.*) } :text :note
.eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
.eh_frame : { KEEP (*(.eh_frame)) } :text
/*
* This linker script is used both with -r and with -shared.
* For the layouts to match, we need to skip more than enough
* space for the dynamic symbol table, etc. If this amount is
* insufficient, ld -shared will error; simply increase it here.
* Text is well-separated from actual data: there's plenty of
* stuff that isn't used at runtime in between.
*/
. = 0x800;
. = ALIGN(16);
.text : { *(.text .text.*) } :text
. = ALIGN(4);